The ß-lactone ring of N-(2-oxo-3-oxetanyl)amides, a class of N-acylethanolamine acid amidase (NAAA) inhibitors endowed with anti-inflammatory properties, is responsible for both NAAA inhibition and low compound stability. Here, we investigated the structure-activity and structure-property relationships for a set of known and new ß-lactone derivatives, focusing on the new class of N-(2-oxo-3-oxetanyl)carbamates. Replacement of the amide group with a carbamate one led to different stereoselectivity for NAAA inhibition and higher intrinsic stability, due to reduced intramolecular attack at the lactone ring. The introduction of a syn methyl at the ß-position of the lactone further improved chemical stability. A tert-butyl substituent in the side chain reduced the reactivity with bovine serum albumin. (2S,3R)-2-methyl-4-oxo-3-oxetanylcarbamic acid 5-phenylpentyl ester (27, URB913/ARN077) inhibited NAAA with good in vitro potency (IC50 = 127 nM) and showed improved stability. It is rapidly cleaved in plasma, which supports its use for topical applications.